Textual analysis: The Book of Mormon adds the phrase "these two sons." The KJV has "These two things..." Ludlow analyzes this shift as follows:
"The description of these two sons calls to mind the two witnesses who will be the major factor in keeping enemy armies from totally defeating the Jews. (Rev. 11:1-6) John the Revelator describes two great servants of God who will stand and fight for Jerusalem against the armies for he world." (Ludlow 1982, p. 431).
This reading is virtually required by verse 20, where "save these two" is an insertion in the text, and a clear referent to the "two sons." The reading, while required, is yet problematic as it requires a complete alteration of the general sense of the text. In order to equate the two sons with the vision of the Revelator, the phrase "who shall be sorry for thee" must be turned from a question to a declarative. In other words, the two sons must be sorry. That does not match the rest of the text. In parallel phrasing in the final "and by whom shall I comfort thee?" clearly shows that this first occurrence is also a question. The emphasis in Isaiah as received is not on a future deliverance by two sons, but on the inability of Israel to produce offspring that will liberate her. Nevertheless, there is an alteration in meaning in the Book of Mormon's Isaiah text which separates out these two sons from the rest of the progeny of Israel, and supplies them with a beneficial (if not completely effective) solution. In the end, they too are "caught in the net."
From a literary standpoint, in the Biblical received Isaiah, the two sons are "thy 'desolation and destruction' and 'famine and the sword'." Even though there are four items, their are paired such that 'desolation and destruction' becomes one thing, and 'famine and the sword' are similarly conjoined into the same calamity (hearkening to the fear of the captive losing his bread? v. 14) This context fits correctly with the intent in the Isaiah text (which has two items, not two sons).
Is the Book of Mormon insertion of "two sons" foreign to the meaning of the text? It is not from a literary sense because the preceding verse has already established the imagery of children. In the context of the poet, the tie from the children of verse 18 to the "two sons" of verse 19 makes complete poetic sense, and provides a tighter composition than the more generic "two things." Thus it is entirely possible, from literary analysis alone, to suggest that the Book of Mormon text might hearken to an older and better reading of the text.
Scriptural analysis: After the Lord admits that their situation is one he has allowed, that it is part of his fury against them, he describes more of the meaning of that "cup of fury." As part of God's wrath, they have been visited by twin desolations of destruction and famine. In the midst of this fury, Israel is incapable of saving herself. There is none among Israel with the power to be moved by sorrow to sufficient action.
Meaning for the Nephite audience: While the provenance of the two sons phrase is not absolutely clear, it is obviously more contextually powerful than "two things" as the separation of the Nephites from the Lamanites must still be an open wound for the Nephites who hear Jacob. However subtle, the "two sons" that are connected to discomforts must have resonated in ways for the Nephite audience that Isaiah never could have understood.